Multilayer plastic containers and preforms typically include one or more layers of plastic matrix resin, such as polyethylene terephthalate (PET), alternating with one or more layers of barrier resin such as polyamide or polyethylene vinyl alcohol copolymer (EVOH) to resist transmission of gas, water vapor and/or flavorants, including odorants and essential oils, through the container wall. Interlaminar adhesion among the several layers of the multilayer wall is necessary in order to resist delamination of these layers and to enhance barrier properties. Furthermore, the plastic material of the matrix layers typically is susceptible to relatively high permeation of substances such as oxygen, carbon dioxide and water through its polymeric/molecular structure. Permeation of these substances, particularly oxygen, can deteriorate the quality of the contents of the product packaged within the container.
In U.S. application Ser. No. 10/688,432, interlaminar adhesion between the several layers of a multilayer plastic container/preform was improved by incorporating at least one layer of a matrix resin, at least one layer of a barrier resin, and an adhesion-promoting material blended with the barrier and/or the matrix resin in the container/preform wall. The matrix resin included an ester-containing resin, preferably a polyester such as PET. The adhesion-promoting material included an amine polymer having a number of available primary, secondary and tertiary amine groups. The barrier resin included EVOH or polyamide.
In U.S. Provisional Application 60/473,024, an active oxygen barrier composition was used to retard oxygen from permeating through a multilayer plastic wall. These active oxygen barrier compositions included one or more polymers and low molecular weight additives. The active oxygen barrier composition included a metal, an additive compound, and possibly a host polymer.
What is needed is a combination of both an adhesive-promoting material and an active oxygen barrier composition in the barrier layer and/or matrix layer of the multilayer plastic container/preform wall that is effective and achieves desirable results. Thus, it is an object of the present invention to provide a multilayer plastic container, preform or article of manufacture having suitable interlaminar adhesion between the several layers of the multilayer wall and has a high barrier against permeation of oxygen therethrough.